408 
MR. E. H. GRIFFITHS OH THE VALUE OF 
touch the central circle. By tightening up a screw in the other end of the bridge a 
good and regular contact was secured. To the centre of each bridge a binding screw 
was fixed, and connection was made by thick wire leads from these to the Carey- 
Foster bridge. 
In the comparison of the units and tens, the Carey-Foster bridge belonging to the 
B,A. was used, and the difference between the standard and the box-unit was found 
in terms of a length of bridge-wire. In the comparison of the lOO’s and lOOO’s, the 
bridge described by Glazebrook (‘B.A. Report,’ 1883) was always used.* 
The standard coils used, and their values, are given in the following Table :— 
Table X. 
Coil. 
Value. 
Elliott 269 . 
1 
+ -000282 {t - 15-1) 
„ 270 . 
1 
+ -000286 {t - 15-3) 
„ 288 . 
10 
+ -00265 {t - 16-2) 
„ 289 . 
10 
-1- -00260 {t - 15-4) 
Nalder 3634 . 
100 
-f -0308 (^ - 17-2) 
„ 3637 . 
100 
+ -0308 (^- 17-05) 
1000 h.w.d . 
05000 + -0000715 (t - 18-2) 
The same thermometer (Hicks, No. 352,601) that had been employed in aU our 
determinations was again used in the standardization, and, since its bore was very 
nearly uniform, no correction was necessary. The B.A. thermometer (K.O., 75,149) 
was used for the temperatures of the standards ; its correction was — TO at the 
temperatures of our observations. 
The resistance of the connections between the box and bridge was taken in terms 
of the bridge-wire of the Carey-Foster bridge. 
The results of observations on different days agree well, the average departure 
from the mean being less than to oVoo* 
The differences could, in most cases, be easily accounted for by small temperature 
changes in the interior of the coils, which could not be indicated by the thermometer. 
The accompanying Table gives the results. 
(Although the coils in the 1000 dials were not used during the determinations of 
the resistance of the calorimeter coil, we have included them in this Table, since many 
of them were required when ascertaining the platinum temperatures, and also because 
a complete standardization of this kind is interesting, as it shows the order of 
accuracy of boxes of this joattern.) 
* In comparing the 100 and 1000 ohms coils, two Leclanche cells were nsed. The currents in the 
battery circuit were '090 and ‘023 ampere respectively. 
